Area Calculator (All Shapes)
Area of rectangle, circle, triangle, polygon + more
Area
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Perimeter
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📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
Free area calculator — 8 shapes
Calculate area of any common 2D shape: rectangle, square, circle, triangle, trapezoid, parallelogram, ellipse, regular polygon. Shows formula + perimeter where applicable.
How to use this tool
- 1
Pick a shape
Rectangle, circle, triangle, trapezoid, parallelogram, ellipse, regular polygon.
- 2
Enter dimensions
Fill in the shape-specific inputs. Formula shown for reference.
- 3
Get area + perimeter
Both calculated instantly. Supports any unit.
Frequently Asked Questions
Triangle with 3 sides (no height)?
Uses Heron's formula: s = (a+b+c)/2, Area = √(s(s-a)(s-b)(s-c)).
Units?
Use any consistent unit. Output will be in square units of whatever you entered (m², ft², cm²).
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100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.